chore: prepare v0.9.0 release

[snimu]

Summary

• bump Prime Agent and all published packages from 0.8.1 to 0.9.0 in lockstep (root included)
• synchronize internal package dependency ranges (^0.9.0) and refresh the lockfile
• fold all 55 post-v0.8.1 change fragments into the 0.9.0 changelogs (51 coding-agent, 3 ai, 1 tui)

Why

0.9.0 ships the event-driven agent roster with pushed updates (#1895/#1897/#1900), direct TUI-to-worker session transport (#1926), the minimal CPython REPL kernel with async bash() (#1684/#1685), daemon startup/recovery hardening (#1929), roster seed scoping without list --all changes (#1951), non-blocking subagent deletion (#1954), inline Mermaid diagrams (#1893), and in-place /update relaunch (#1631), plus the full bug-fix set in the changelogs.

Linear: ENG-5839 (release tracking)

Validation

• full test gate in a Prime sandbox at the release base (3da8c5a1c), mirroring the CI matrix:
  • npm run build — pass
  • root npm run check (biome, tsgo, installer render, browser smoke) — pass
  • packages/ai 341 passed, packages/agent 70 passed, packages/tui 766 passed
  • packages/coding-agent test:ci shards 1–3: 4,559 passed; test:process 11 passed; test:kernel 15 passed
  • prime-agent-runtime Python suite: 269 passed
  • only failures: 4 tests in 3 files, all in the documented environmental baseline (root-user EACCES class); zero new failing files
• root npm run check re-run locally on the release branch after the bump + changelog aggregation — pass
• node scripts/sync-versions.js — lockstep confirmed, dependent ranges synced
• verified no example or private workspace versions were bumped to 0.9.0 (examples keep their own versions; only the lockfile references updated)
• lockfile refreshed minimally from main's lockfile (15-line diff) rather than regenerated from scratch: a fresh regen drifted @mistralai/mistralai to a version whose optional otel import breaks esbuild's browser-smoke bundling (dev-time check only; end-user installs resolve ranges independently and are unaffected — verified by importing the drifted version under plain Node)
• changelog markdown audited for unmarked list entries after the bot caught one missing - (fixed in 19a2884)

Release sequencing

This PR prepares the release only — no tag, no publish. After merge: tag v0.9.0 and npm run publish per scripts/release.mjs. Note for the next release: npm run version:minor fails mid-script on 0.x minor bumps (caret ranges can't resolve the new version before sync-versions.js runs); the steps were completed manually here.

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Note

Low Risk
Release-metadata only (versions, lockfile, changelogs); no runtime code changes in the diff.

Overview
Cuts the v0.9.0 release by bumping the root and all workspace packages from 0.8.1 to 0.9.0, aligning internal dependency ranges to ^0.9.0, and refreshing package-lock.json (including example extensions such as sandbox 1.4.0→1.5.0).

Changelog hygiene: pending .changes/ fragments are folded into dated [0.9.0] - 2026-09-01 sections in packages/ai, packages/coding-agent, and packages/tui CHANGELOGs, then the fragment files are removed. The coding-agent entry documents the shipped work (REPL kernel cutover, async bash(), agent roster push, direct session transport, daemon recovery, Mermaid diagrams, etc.); ai and tui entries are smaller (model catalog / overflow helper / Markdown transform hook).

This PR does not change application source—only versions, lockfiles, and release notes. Tag and npm publish follow merge per the release script.

^{Reviewed by Cursor Bugbot for commit 19a2884. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Bump workspace packages to v0.9.0

Bumps versions from 0.8.1 to 0.9.0 across root and all package package.json files, and updates internal cross-package dependencies accordingly. Consolidates accumulated changeset notes into the CHANGELOG.md entries for @earendil-works/pi-ai, @earendil-works/pi-coding-agent, and @earendil-works/pi-tui, then deletes the consumed changeset files. Example extensions under packages/coding-agent/examples/extensions/ also receive version bumps.

^{Macroscope summarized 19a2884.}